Electrical transformer



(No Model.) 2 Sheets-Sheet 1.

W. S. MOODY. ELECTRICAL TRANSFORMER.

No. 567,250. tdSept. 8, 18 96,

G /l6 l2 /0 Mi 16/1 16 F32. F5 1 WITNESSES- g 2 SheetsSheet 2.

.(No Model.)

' W. S. MOODY.

v ELEGTRIOAL TRANSFORMER.

G 0 m n l 8 :I 1 fin m 8 a Q m P n 6 L S w u m n a m I I I l l l I I I I I I l I I I l I I |l| aw P W Z l I I I I I l l I I l 1 I I I I l l l- UNITED STATES PATENT OFFICE.

WALTER s. MOODY, or LYNN, ssAonUs r'rs, ASSIGNOR TO THE GENERAL ELEorRIo COMPANY, OF NEW YORK.

ELECTRICAL TRANSFORMER.

SPECIFICATION forming part of Letters Patent No. 567,250, dated September 8, 1896. Application filed March 30, 1896. Serial No. 585,834. (No model.)

To all whom it may concernr Be it known that I, WALTER S. MOODY, a acitizen of the United States,residing at Lynn, in the county of Essex, State of Massachusetts, have invented certain new and useful ImprovementsinTransformers(Case No. 316,) of which the following is a specification.

This invention relates to transformers, and has for its object to provide an improved core for transformers formed of built-up groups of laminae constructed and arranged as hereinafter set forth and claimed.

Referring to the accompanying drawings, Figure 1 is a perspective view in elevation of a core constructed in accordance with this invention. Fig. 2 is a detail view of one of the laminae forming the core. Fig. 3 is a perspective view in elevation of a modified form of core incompleted. Figs. 4 and 5 are detail views of laminae forming the core. Fig. 6 is a perspective view of a modificatiomshowing a portion of the laminae. Fig. 6 is a side view in elevation and partly in section showing part of the casing removed of a transformer 2 5 constructed in accordancewith this invention. Fig. 7 is an end view thereof in elevation. Fig. 8 is a top plan view. Fig. 9 is aview of the top cap of the core. Fig. 10 is an edge view thereof, partly broken away. Figs. 11, o 12, and 13 are edge, plan, and transverse sectional views of the bottom supporting-plate of the core.

Referring now to Fig. 1, one form of build ing up the core is as follows: Sheet-iron is cut 3 5 up into strips or laminae of two sizes, consisting of longpieces 1 and short pieces 2. These pieces are rectangular, and thereby there is no waste of material in cutting. The long pieces 1 are assembled in small groups of three or four pieces, more or less, each group overlapping an adjacent group at one end and being correspondingly shorter than its neighbor at the other end; or, in other words, the groups are alternately mismatched, so that 5 when the laminae have been built up to the desired thickness there is formed at each end a tongue-and-groove arrangement, as shown. The winding 3 is then placed about the longer bundle of laminae 1, as shown in Figs. 6, '7, and 8, the secondary coil being wound next to the core with the usual insulation interposed and the primary being wound without the secondary so as to remove it far away from the core. The winding is effected by clamping the ends of the bundle of laminae in 5 5 a frame of a winding-machine, the work of insulating and winding being much facilitated in this way. Both upright or longer portions of the core are so wound, and the primary and secondary coils maytherefore be conveniently connected in multiple or in series, respectively, to accommodate themselves to the potential of the circuits to which they are tobe connected. The windings and insulationof the core also serve to hold the laminae together after the core is removed from the frame of the winding-machine.

To complete the core of the transformer, two of the aforesaid wound bundles of long laminae are placed at a suitable distance apart, and the tongueand-grooved ends thereof are provided with bundles of short laminae 2, as shown in Fig. 1, their ends filling the grooves on one side and abutting against the ends of the long laminae 011 the other side, the groups thereby breaking joint and providing a magnetic core having a low magnetic resistance.

The sections of the core are locked and held in position by the metallic end caps 4L 5, which are slipped over the ends of the core, and are separated therefrom by wooden strips 6 and wooden wedges 7, driven in to hold the parts firmly in place. The bottom cap 5 has feet or projections 8, which rest on the bottom of the transformer-casing 9, and the top cap 4 has lugs 10, which rest upon a ledge or flange 11 of the casing 9, the core being secured to the casing by bolts and nuts 12, engaging some of the lugs 10.

In the modification shown in Fig. 3 the con- 0 struction is similar to that in Fig. 1, except that the bundles of long pieces 13 are not mismatched or overlapping with respect to each other, but are of equal length, with a bundle of short laminae 14 inserted between each pair 9 5 of bundles of long laminae 13, forming grooved joints at the ends of the core, in which rest the ends of the bundles of short laminae 14. By means of this arrangement open air-spaces 15 are provided at the ends of the core. The cross-section of the metal would therefore be reduced at this point; but provision is made for that by increasing the thickness of the bundles of laminae forming the ends of the core. An advantage of the ventilating-openingslies in increasing the cooling effects on the structure. The transformer-casing may or may not be filled with oil, as desired. It will be noted that but two sizes of laminae are required in the construction of the core. If desired, however, in the construction of Fig. 3, three sizes of punchings may be employedviz, the longer and shorter laminae of the sides and the laminae of the ends of the core being each of a different size.

To facilitate the assembling of the side laminae, holes 16 are punched therein, those in Fig. 1 being located at uneven distances from the ends of the laminae. A number of laminae, with their holes matching, are slipped over suitably-spaced pins 16', and so on in groups to form the offset arrangement de scribed. Before being wound with coils the bundle of sheet-iron laminae assembled to the desired thickness are provided with U shaped caps 17, of strong red fiber paper, having its inner surface covered with shellac, said caps being placed over the sides, and after the bundle is forced into a compact mass in a powerful press the shellaeked paper is secured to the core and t0 the opposite cap by being subjected to the pressure of a heated iron, which softens the shellac an d causes the parts to adhere firmly. In smaller sizes of trans former each lamina may overlap its neighbor instead of overlapping by groups. Further, in assembling the side laminae it should be added that these pins 10 are made of wood, and when the sheets are piled up upon the plates of the press or bed of the press the pins 16 pass through openings suitably provided in the upper plate of the press during com pression, and after the strong fiber paper has been shellacked in place to hold the laminae in their compacted position the pins 10 are cut off flush with the surface. By means of these pins 16 he slipping of the individual sheets of the core over each otheris prevented and the bundle remains square or rectangular. Moreover, and of still greater importance, this mode of working obviates the use of insulated metallic bolts to hold the laminae together after compression, which must needs have a nut forming a projection which breaks up the surface and requires additional insulation, whereas the wooden pins and paperfiber together make an advantageous substitute.

lVhen the bundles of laminae have been arranged in proper order-that is, with alternatelyoverlapping ends, as described-and this delay and afford a quick means of determining the proper place for the insertion of the end laminae, one corner of each lamina is cut off, as at 17, and during assembling they are matched so that these cut-off corners 17 are found in line at the bottom of the grooves formed between the adjacent sets of laminae, iand thus make it easy for the workman to j quickly divide the laminae into their proper groupings when he is inserting the end laminae, the cut-off corners 17 being readily discernible by the eye, and the end laminae are of course inserted as groups comprising the same number of sheets as the side laminae or bundles.

Considering the transformer electrically, it will be noted that the loss due to leakage magnetism is reduced to a minimum owing to the relatively great distance between the ends of the core.

lVhat I claim is-- 1. A transformer consisting of a built-up core, having its sides composed of bundles of metallic laminae with overlapping ends, and its ends composed of bundles of metallic launinae breaking joint with the sides, shellaeked fiber paper wrapped around the side laminae, insulating pins securing the latter together, and windings about the sides of the core.

2. In an electrical transformer the combination of, a core or coil carrying portion consisting of an assemblage of rectangular sheet-iron laminae, each sheet having spacing-holes sit uated at points unequally distant from the ends of the sheet, spacing and stiffening pins of non-magnetic insulating material, such as wood, in said holes having a flush surface with the outer face of the sheets, a fibrous insulating covering or wrapping serving to retain said sheets in their compressed relation as assembled upon said pins, inducing and induced windings upon said core, and bundles of sheet-iron laminae joining the ends of said core and adapted to complete the magnetic cir uit, as described.

WALTER S. MOODY.

Vitnesses JOHN W. GIBBONEY, EDWIN R. PEARson. 

